The Syrian government and the rebels fighting against it carried out a massive prisoner swap Wednesday, with the government releasing 2,130 Syrian and Turkish captives in exchange for 48 Iranians who had been seized by rebel forces.

The swap appeared to be the largest yet in the nearly two-year-old conflict, which has left up to 60,000 dead. The deal was brokered by the governments of Qatar and Turkey. A Turkish humanitarian group that has helped in previous exchanges facilitated the prisoners’ release.

Critics of beleaguered Syrian President Bashar al-Assad said the lopsided deal highlights how much he is influenced by Iran, one of the Syrian government’s last remaining allies. They noted that Assad did not insist on the release of any of the hundreds of Syrian soldiers who have been captured by the rebels, focusing instead on the Iranian prisoners.